Signal detection in unknown interference channels

In many realistic communication environments, experiments supported by theoretical considerations indicate that the overall noise statistics deviate from the Gaussian distribution due to the presence of high amplitude interference. The decoding in non-Gaussian noise is complicated by the fact that accurate noise statistics are typically unavailable at the receiver. Without exploiting the noise probability density function (pdf), the widely accepted method is to erase the symbols corrupted by the high amplitude interference before an error-and-erasure decoding is performed. The accuracy of the erasure marking determines the decoding performance. In this thesis, we propose a joint erasure marking and decoding (JED) approach, which exploits the code structure in erasure marking such that the erasures can be marked more accurately. The JED is investigated from the theoretical aspects to the application aspects.; Firstly, we study the theoretical aspects of JED including the geometric characterization of the decision region and the performance analysis.; We then implement the JED in trellises and derive the joint erasure marking and Viterbi algorithm (JEVA). With a self-contained criterion to determine the number of erasures to mark, the performance of JEVA approaches that of the optimal maximum likelihood decoder that exploits the exact noise pdf. To trade off the computation complexity, decoding delay and memory requirement, several variants of JEVA are also presented.; To further improve the performance of JEVA, we integrate JEVA with the list Viterbi algorithm (LVA) and propose the joint erasure marking and list Viterbi algorithm (JELVA). The JELVA provides two degrees of freedom in marking erasures and significantly improves the performance of JEVA.; Finally, we apply the idea of joint erasure marking and decoding to cognitive radio systems. Due to the bursty nature of interference in cognitive radio systems, the t interference cannot be fully detected by pilots. To combat the residual undetected interference in the data packet, we apply a tailored joint erasure marking and decoding scheme for such systems. The proposed scheme is able to successfully detect the interference and achieve a performance close to that of the optimal decoder that exploits the full interference knowledge including the frequency band and the power.